@phdthesis{Rezaei2019,
  author    = {Rezaei, Mina},
  title     = {Deep representation learning from imbalanced medical imaging},
  doi       = {10.25932/publishup-44275},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-442759},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xxviii, 160},
  year      = {2019},
  abstract  = {Medical imaging plays an important role in disease diagnosis, treatment planning, and clinical monitoring. One of the major challenges in medical image analysis is imbalanced training data, in which the class of interest is much rarer than the other classes. Canonical machine learning algorithms suppose that the number of samples from different classes in the training dataset is roughly similar or balance. Training a machine learning model on an imbalanced dataset can introduce unique challenges to the learning problem. A model learned from imbalanced training data is biased towards the high-frequency samples. The predicted results of such networks have low sensitivity and high precision. In medical applications, the cost of misclassification of the minority class could be more than the cost of misclassification of the majority class. For example, the risk of not detecting a tumor could be much higher than referring to a healthy subject to a doctor. The current Ph.D. thesis introduces several deep learning-based approaches for handling class imbalanced problems for learning multi-task such as disease classification and semantic segmentation. At the data-level, the objective is to balance the data distribution through re-sampling the data space: we propose novel approaches to correct internal bias towards fewer frequency samples. These approaches include patient-wise batch sampling, complimentary labels, supervised and unsupervised minority oversampling using generative adversarial networks for all. On the other hand, at algorithm-level, we modify the learning algorithm to alleviate the bias towards majority classes. In this regard, we propose different generative adversarial networks for cost-sensitive learning, ensemble learning, and mutual learning to deal with highly imbalanced imaging data. We show evidence that the proposed approaches are applicable to different types of medical images of varied sizes on different applications of routine clinical tasks, such as disease classification and semantic segmentation. Our various implemented algorithms have shown outstanding results on different medical imaging challenges.},
  language  = {en}
}
@phdthesis{Reeg2019,
  author    = {Reeg, Jette},
  title     = {Simulating the impact of herbicide drift exposure on non-target terrestrial plant communities},
  doi       = {10.25932/publishup-42907},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-429073},
  school      = {Universit{\"a}t Potsdam},
  pages     = {178},
  year      = {2019},
  abstract  = {In Europe, almost half of the terrestrial landscape is used for agriculture. Thus, semi-natural habitats such as field margins are substantial for maintaining diversity in intensively managed farmlands. However, plants located at field margins are threatened by agricultural practices such as the application of pesticides within the fields. Pesticides are chemicals developed to control for undesired species within agricultural fields to enhance yields. The use of pesticides implies, however, effects on non-target organisms within and outside of the agricultural fields. Non-target organisms are organisms not intended to be sprayed or controlled for. For example, plants occurring in field margins are not intended to be sprayed, however, can be impaired due to herbicide drift exposure. The authorization of plant protection products such as herbicides requires risk assessments to ensure that the application of the product has no unacceptable effects on the environment. For non-target terrestrial plants (NTTPs), the risk assessment is based on standardized greenhouse studies on plant individual level. To account for the protection of plant populations and communities under realistic field conditions, i.e. extrapolating from greenhouse studies to field conditions and from individual-level to community-level, assessment factors are applied. However, recent studies question the current risk assessment scheme to meet the specific protection goals for non-target terrestrial plants as suggested by the European Food Safety Authority (EFSA). There is a need to clarify the gaps of the current risk assessment and to include suitable higher tier options in the upcoming guidance document for non-target terrestrial plants. In my thesis, I studied the impact of herbicide drift exposure on NTTP communities using a mechanistic modelling approach. I addressed main gaps and uncertainties of the current risk assessment and finally suggested this modelling approach as a novel higher tier option in future risk assessments. Specifically, I extended the plant community model IBC-grass (Individual-based community model for grasslands) to reflect herbicide impacts on plant individuals. In the first study, I compared model predictions of short-term herbicide impacts on artificial plant communities with empirical data. I demonstrated the capability of the model to realistically reflect herbicide impacts. In the second study, I addressed the research question whether or not reproductive endpoints need to be included in future risk assessments to protect plant populations and communities. I compared the consequences of theoretical herbicide impacts on different plant attributes for long-term plant population dynamics in the community context. I concluded that reproductive endpoints only need to be considered if the herbicide effect is assumed to be very high. The endpoints measured in the current vegetative vigour and seedling emergence studies had high impacts for the dynamic of plant populations and communities already at lower effect intensities. Finally, the third study analysed long-term impacts of herbicide application for three different plant communities. This study highlighted the suitability of the modelling approach to simulate different communities and thus detecting sensitive environmental conditions. Overall, my thesis demonstrates the suitability of mechanistic modelling approaches to be used as higher tier options for risk assessments. Specifically, IBC-grass can incorporate available individual-level effect data of standardized greenhouse experiments to extrapolate to community-level under various environmental conditions. Thus, future risk assessments can be improved by detecting sensitive scenarios and including worst-case impacts on non-target plant communities.},
  language  = {en}
}
@phdthesis{Rector2019,
  author    = {Rector, Michael V.},
  title     = {The acute effect of exercise on flow-mediated dilation in young people with cystic fibrosis},
  doi       = {10.25932/publishup-43893},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-438938},
  school      = {Universit{\"a}t Potsdam},
  pages     = {121},
  year      = {2019},
  abstract  = {Introduction: Cystic fibrosis (CF) is a genetic disease which disrupts the function of an epithelial surface anion channel, CFTR (cystic fibrosis transmembrane conductance regulator). Impairment to this channel leads to inflammation and infection in the lung causing the majority of morbidity and mortality. However, CF is a multiorgan disease affecting many tissues, including vascular smooth muscle. Studies have revealed young people with cystic fibrosis lacking inflammation and infection still demonstrate vascular endothelial dysfunction, measured per flow-mediated dilation (FMD). In other disease cohorts, i.e. diabetic and obese, endurance exercise interventions have been shown improve or taper this impairment. However, long-term exercise interventions are risky, as well as costly in terms of time and resources. Nevertheless, emerging research has correlated the acute effects of exercise with its long-term benefits and advocates the study of acute exercise effects on FMD prior to longitudinal studies. The acute effects of exercise on FMD have previously not been examined in young people with CF, but could yield insights on the potential benefits of long-term exercise interventions. The aims of these studies were to 1) develop and test the reliability of the FMD method and its applicability to study acute exercise effects; 2) compare baseline FMD and the acute exercise effect on FMD between young people with and without CF; and 3) explore associations between the acute effects of exercise on FMD and demographic characteristics, physical activity levels, lung function, maximal exercise capacity or inflammatory hsCRP levels. Methods: Thirty young volunteers (10 people with CF, 10 non-CF and 10 non-CF active matched controls) between the ages of 10 and 30 years old completed blood draws, pulmonary function tests, maximal exercise capacity tests and baseline FMD measurements, before returning approximately 1 week later and performing a 30-min constant load training at 75\% HRmax. FMD measurements were taken prior, immediately after, 30 minutes after and 1 hour after constant load training. ANOVAs and repeated measures ANOVAs were employed to explore differences between groups and timepoints, respectively. Linear regression was implemented and evaluated to assess correlations between FMD and demographic characteristics, physical activity levels, lung function, maximal exercise capacity or inflammatory hsCRP levels. For all comparisons, statistical significance was set at a p-value of α < 0.05. Results: Young people with CF presented with decreased lung function and maximal exercise capacity compared to matched controls. Baseline FMD was also significantly decreased in the CF group (CF: 5.23\% v non-CF: 8.27\% v non-CF active: 9.12\%). Immediately post-training, FMD was significantly attenuated (approximately 40\%) in all groups with CF still demonstrating the most minimal FMD. Follow-up measurements of FMD revealed a slow recovery towards baseline values 30 min post-training and improvements in the CF and non-CF active groups 60 min post-training. Linear regression exposed significant correlations between maximal exercise capacity (VO2 peak), BMI and FMD immediately post-training. Conclusion: These new findings confirm that CF vascular endothelial dysfunction can be acutely modified by exercise and will aid in underlining the importance of exercise in CF populations. The potential benefits of long-term exercise interventions on vascular endothelial dysfunction in young people with CF warrants further investigation.},
  language  = {en}
}
@phdthesis{Ramachandran2019,
  author    = {Ramachandran, Varsha},
  title     = {Massive star evolution, star formation, and feedback at low metallicity},
  doi       = {10.25932/publishup-43245},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-432455},
  school      = {Universit{\"a}t Potsdam},
  pages     = {291},
  year      = {2019},
  abstract  = {The goal of this thesis is to broaden the empirical basis for a better, comprehensive understanding of massive star evolution, star formation and feedback at low metallicity. Low metallicity massive stars are a key to understand the early universe. Quantitative information on metal-poor massive stars was sparse before. The quantitative spectroscopic studies of massive star populations associated with large-scale ISM structures were not performed at low metallicity before, but are important to investigate star-formation histories and feedback in detail. Much of this work relies on spectroscopic observations with VLT-FLAMES of ~500 OB stars in the Magellanic Clouds. When available, the optical spectroscopy was complemented by UV spectra from the HST, IUE, and FUSE archives. The two representative young stellar populations that have been studied are associated with the superbubble N 206 in the Large Magellanic Cloud (LMC) and with the supergiant shell SMC-SGS 1 in the Wing of the Small Magellanic Cloud (SMC), respectively. We performed spectroscopic analyses of the massive stars using the nonLTE Potsdam Wolf-Rayet (PoWR) model atmosphere code. We estimated the stellar, wind, and feedback parameters of the individual massive stars and established their statistical distributions. The mass-loss rates of N206 OB stars are consistent with theoretical expectations for LMC metallicity. The most massive and youngest stars show nitrogen enrichment at their surface and are found to be slower rotators than the rest of the sample. The N 206 complex has undergone star formation episodes since more than 30 Myr, with a current star formation rate higher than average in the LMC. The spatial age distribution of stars across the complex possibly indicates triggered star formation due to the expansion of the superbubble. Three very massive, young Of stars in the region dominate the ionizing and mechanical feedback among hundreds of other OB stars in the sample. The current stellar wind feedback rate from the two WR stars in the complex is comparable to that released by the whole OB sample. We see only a minor fraction of this stellar wind feedback converted into X-ray emission. In this LMC complex, stellar winds and supernovae equally contribute to the total energy feedback, which eventually powered the central superbubble. However, the total energy input accumulated over the time scale of the superbubble significantly exceeds the observed energy content of the complex. The lack of energy along with the morphology of the complex suggests a leakage of hot gas from the superbubble. With a detailed spectroscopic study of massive stars in SMC-SGS 1, we provide the stellar and wind parameters of a large sample of OB stars at low metallicity, including those in the lower mass-range. The stellar rotation velocities show a broad, tentatively bimodal distribution, with Be stars being among the fastest. A few very luminous O stars are found close to the main sequence, while all other, slightly evolved stars obey a strict luminosity limit. Considering additional massive stars in evolved stages, with published parameters and located all over the SMC, essentially confirms this picture. The comparison with single-star evolutionary tracks suggests a dichotomy in the fate of massive stars in the SMC. Only stars with an initial mass below 30 solar masses seem to evolve from the main sequence to the cool side of the HRD to become a red supergiant and to explode as type II-P supernova. In contrast, more massive stars appear to stay always hot and might evolve quasi chemically homogeneously, finally collapsing to relatively massive black holes. However, we find no indication that chemical mixing is correlated with rapid rotation. We measured the key parameters of stellar feedback and established the links between the rates of star formation and supernovae. Our study demonstrates that in metal-poor environments stellar feedback is dominated by core-collapse supernovae in combination with winds and ionizing radiation supplied by a few of the most massive stars. We found indications of the stochastic mode of star formation, where the resulting stellar population is fully capable of producing large-scale structures such as the supergiant shell SMC-SGS 1 in the Wing. The low level of feedback in metal-poor stellar populations allows star formation episodes to persist over long timescales. Our study showcases the importance of quantitative spectroscopy of massive stars with adequate stellar-atmosphere models in order to understand star-formation, evolution, and feedback. The stellar population analyses in the LMC and SMC make us understand that massive stars and their impact can be very different depending on their environment. Obviously, due to their different metallicity, the massive stars in the LMC and the SMC follow different evolutionary paths. Their winds differ significantly, and the key feedback agents are different. As a consequence, the star formation can proceed in different modes.},
  language  = {en}
}
@phdthesis{Rabe2019,
  author    = {Rabe, Sophie},
  title     = {Wirksamkeit einer telemedizinisch assistierten Bewegungstherapie f{\"u}r die postrehabilitative Versorgung von Patienten mit Knie- oder H{\"u}ft-Totalendoprothese im berufsf{\"a}higen Alter},
  doi       = {10.25932/publishup-43055},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-430556},
  school      = {Universit{\"a}t Potsdam},
  pages     = {x, 78},
  year      = {2019},
  abstract  = {Einleitung Die Implantation einer Knie- oder H{\"u}ft-Totalendoprothese (TEP) ist eine der h{\"a}ufigsten operativen Eingriffe. Im Anschluss an die Operation und die postoperative Rehabilitation stellt die Bewegungstherapie einen wesentlichen Bestandteil der Behandlung zur Verbesserung der Gelenkfunktion und der Lebensqualit{\"a}t dar. In strukturschwachen Gebieten werden entsprechende Angebote nur in unzureichender Dichte vorgehalten. Zudem zeichnet sich ein fl{\"a}chendeckender Fachkr{\"a}ftemangel im Bereich der Physiotherapie ab. Die Tele-Nachsorge bietet daher einen innovativen Ansatz f{\"u}r die postrehabilitative Versorgung der Patienten. Das Ziel der vorliegenden Untersuchung war die {\"U}berpr{\"u}fung der Wirksamkeit einer interaktiven Tele-Nachsorgeintervention f{\"u}r Patienten mit Knie- oder H{\"u}ft-TEP im Vergleich zur herk{\"o}mmlichen Versorgung (usual care). Dazu wurden die Funktionalit{\"a}t und die berufliche Wiedereingliederung untersucht. Methode Zwischen August 2016 und August 2017 wurden 111 Patienten (54,9 ± 6,8 Jahre, 54,3 \% weiblich) zu Beginn ihrer station{\"a}ren Anschlussheilbehandlung nach Implantation einer Knie- oder H{\"u}ft-TEP in diese randomisiert, kontrolliert, multizentrische Studie eingeschlossen. Nach Entlassung aus der orthop{\"a}dischen Anschlussrehabilitation (Baseline) f{\"u}hrte die Interventionsgruppe (IG) ein dreimonatiges interaktives Training {\"u}ber ein Telerehabilitationssystem durch. Hierf{\"u}r erstellte ein betreuender Physiotherapeut einen individuellen Trainingsplan aus 38 {\"U}bungen zur Verbesserung der Kraft sowie der posturalen Kontrolle. Zur Anpassung des Trainingsplans {\"u}bermittelte das System dem Physiotherapeuten Daten zur Quantit{\"a}t sowie zur Qualit{\"a}t des Trainings. Die Kontrollgruppe (KG) konnte die herk{\"o}mmlichen Versorgungsangebote nutzen. Zur Beurteilung der Wirksamkeit der Intervention wurde die Differenz der Verbesserung im 6MWT zwischen der IG und der KG nach drei Monaten als prim{\"a}rer Endpunkt definiert. Als sekund{\"a}re Endpunkte wurden die Return-to-Work-Rate sowie die funktionelle Mobilit{\"a}t mittels des Stair Ascend Tests, des Five-Times-Sit-to-Stand Test und des Timed Up and Go Tests untersucht. Weiterhin wurden die gesundheitsbezogene Lebensqualit{\"a}t mit dem Short-Form 36 (SF-36) und die gelenkbezogenen Einschr{\"a}nkungen mit dem Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) evaluiert. Der prim{\"a}re und die sekund{\"a}ren Endpunkte wurden anhand von baseline-adjustierten Kovarianzanalysen im intention-to-treat-Ansatz ausgewertet. Zus{\"a}tzlich wurde die Teilnahme an Nachsorgeangeboten und die Adh{\"a}renz der Interventionsgruppe an der Tele-Nachsorge erfasst und evaluiert. Ergebnisse Zum Ende der Intervention wiesen beide Gruppen einen statistisch signifikanten Anstieg ihrer 6MWT Strecke auf (p < 0,001). Zu diesem Zeitpunkt legten die Teilnehmer der IG im Mittel 530,8 ± 79,7 m, die der KG 514,2 ± 71,2 m zur{\"u}ck. Dabei betrug die Differenz der Verbesserung der Gehstrecke in der IG 88,3 ± 57,7 m und in der KG 79,6 ± 48,7 m. Damit zeigt der prim{\"a}re Endpunkt keine signifikanten Gruppenunterschiede (p = 0,951). Bez{\"u}glich der beruflichen Wiedereingliederung konnte jedoch eine signifikant h{\"o}here Rate in der IG (64,6 \% versus 46,2 \%; p = 0,014) festgestellt werden. F{\"u}r die sekund{\"a}ren Endpunkte der funktionellen Mobilit{\"a}t, der Lebensqualit{\"a}t und der gelenkbezogenen Beschwerden belegen die Ergebnisse eine Gleichwertigkeit beider Gruppen zum Ende der Intervention. Schlussfolgerung Die telemedizinisch assistierte Bewegungstherapie f{\"u}r Knie- oder H{\"u}ft-TEP Patienten ist der herk{\"o}mmlichen Versorgung zur Nachsorge hinsichtlich der erzielten Verbesserungen der funktionellen Mobilit{\"a}t, der gesundheitsbezogenen Lebensqualit{\"a}t und der gelenkbezogenen Beschwerden gleichwertig. In dieser Patientenpopulation ließen sich klinisch relevante Verbesserungen unabh{\"a}ngig von der Form der Bewegungstherapie erzielen. Im Hinblick auf die berufliche Wiedereingliederung zeigte sich eine signifikant h{\"o}here Rate in der Interventionsgruppe. Die telemedizinisch assistierte Bewegungstherapie scheint eine geeignete Versorgungsform der Nachsorge zu sein, die orts- und zeitunabh{\"a}ngig durchgef{\"u}hrt werden kann und somit den Bed{\"u}rfnissen berufst{\"a}tiger Patienten entgegenkommt und in den Alltag der Patienten integriert werden kann. Die Tele-Nachsorge sollte daher als optionale und komplement{\"a}re Form der postrehabilitativen Nachsorge angeboten werden. Auch im Hinblick auf den zunehmenden Fachkr{\"a}ftemangel im Bereich der Physiotherapie und bestehende Versorgungsl{\"u}cken in strukturschwachen Gebieten kann der Einsatz der Tele-Nachsorge innovative und bedarfsgerechte L{\"o}sungsans{\"a}tze bieten.},
  language  = {de}
}
@phdthesis{Raatz2019,
  author    = {Raatz, Michael},
  title     = {Strategies within predator-prey interactions - from individuals to ecosystems},
  doi       = {10.25932/publishup-42658},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-426587},
  school      = {Universit{\"a}t Potsdam},
  pages     = {175},
  year      = {2019},
  abstract  = {Predator-prey interactions provide central links in food webs. These interaction are directly or indirectly impacted by a number of factors. These factors range from physiological characteristics of individual organisms, over specifics of their interaction to impacts of the environment. They may generate the potential for the application of different strategies by predators and prey. Within this thesis, I modelled predator-prey interactions and investigated a broad range of different factors driving the application of certain strategies, that affect the individuals or their populations. In doing so, I focused on phytoplankton-zooplankton systems as established model systems of predator-prey interactions. At the level of predator physiology I proposed, and partly confirmed, adaptations to fluctuating availability of co-limiting nutrients as beneficial strategies. These may allow to store ingested nutrients or to regulate the effort put into nutrient assimilation. We found that these two strategies are beneficial at different fluctuation frequencies of the nutrients, but may positively interact at intermediate frequencies. The corresponding experiments supported our model results. We found that the temporal structure of nutrient fluctuations indeed has strong effects on the juvenile somatic growth rate of {\itshape Daphnia}. Predator colimitation by energy and essential biochemical nutrients gave rise to another physiological strategy. High-quality prey species may render themselves indispensable in a scenario of predator-mediated coexistence by being the only source of essential biochemical nutrients, such as cholesterol. Thereby, the high-quality prey may even compensate for a lacking defense and ensure its persistence in competition with other more defended prey species. We found a similar effect in a model where algae and bacteria compete for nutrients. Now, being the only source of a compound that is required by the competitor (bacteria) prevented the competitive exclusion of the algae. In this case, the essential compounds were the organic carbon provided by the algae. Here again, being indispensable served as a prey strategy that ensured its coexistence. The latter scenario also gave rise to the application of the two metabolic strategies of autotrophy and heterotrophy by algae and bacteria, respectively. We found that their coexistence allowed the recycling of resources in a microbial loop that would otherwise be lost. Instead, these resources were made available to higher trophic levels, increasing the trophic transfer efficiency in food webs. The predation process comprises the next higher level of factors shaping the predator-prey interaction, besides these factors that originated from the functioning or composition of individuals. Here, I focused on defensive mechanisms and investigated multiple scenarios of static or adaptive combinations of prey defense and predator offense. I confirmed and extended earlier reports on the coexistence-promoting effects of partially lower palatability of the prey community. When bacteria and algae are coexisting, a higher palatability of bacteria may increase the average predator biomass, with the side effect of making the population dynamics more regular. This may facilitate experimental investigations and interpretations. If defense and offense are adaptive, this allows organisms to maximize their growth rate. Besides this fitness-enhancing effect, I found that co-adaptation may provide the predator-prey system with the flexibility to buffer external perturbations. On top of these rather internal factors, environmental drivers also affect predator-prey interactions. I showed that environmental nutrient fluctuations may create a spatio-temporal resource heterogeneity that selects for different predator strategies. I hypothesized that this might favour either storage or acclimation specialists, depending on the frequency of the environmental fluctuations. We found that many of these factors promote the coexistence of different strategies and may therefore support and sustain biodiversity. Thus, they might be relevant for the maintenance of crucial ecosystem functions that also affect us humans. Besides this, the richness of factors that impact predator-prey interactions might explain why so many species, especially in the planktonic regime, are able to coexist.},
  language  = {en}
}
@phdthesis{Qin2019,
  author    = {Qin, Qing},
  title     = {Chemical functionalization of porous carbon-based materials to enable novel modes for efficient electrochemical N2 fixation},
  doi       = {10.25932/publishup-44339},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-443397},
  school      = {Universit{\"a}t Potsdam},
  pages     = {146},
  year      = {2019},
  abstract  = {The central motivation of the thesis was to provide possible solutions and concepts to improve the performance (e.g. activity and selectivity) of electrochemical N2 reduction reaction (NRR). Given that porous carbon-based materials usually exhibit a broad range of structural properties, they could be promising NRR catalysts. Therefore, the advanced design of novel porous carbon-based materials and the investigation of their application in electrocatalytic NRR including the particular reaction mechanisms are the most crucial points to be addressed. In this regard, three main topics were investigated. All of them are related to the functionalization of porous carbon for electrochemical NRR or other electrocatalytic reactions. In chapter 3, a novel C-TixOy/C nanocomposite has been described that has been obtained via simple pyrolysis of MIL-125(Ti). A novel mode for N2 activation is achieved by doping carbon atoms from nearby porous carbon into the anion lattice of TixOy. By comparing the NRR performance of M-Ts and by carrying out DFT calculations, it is found that the existence of (O-)Ti-C bonds in C-doped TixOy can largely improve the ability to activate and reduce N2 as compared to unoccupied OVs in TiO2. The strategy of rationally doping heteroatoms into the anion lattice of transition metal oxides to create active centers may open many new opportunities beyond the use of noble metal-based catalysts also for other reactions that require the activation of small molecules as well. In chapter 4, a novel catalyst construction composed of Au single atoms decorated on the surface of NDPCs was reported. The introduction of Au single atoms leads to active reaction sites, which are stabilized by the N species present in NDPCs. Thus, the interaction within as-prepared AuSAs-NDPCs catalysts enabled promising performance for electrochemical NRR. For the reaction mechanism, Au single sites and N or C species can act as Frustrated Lewis pairs (FLPs) to enhance the electron donation and back-donation process to activate N2 molecules. This work provides new opportunities for catalyst design in order to achieve efficient N2 fixation at ambient conditions by utilizing recycled electric energy. The last topic described in chapter 5 mainly focused on the synthesis of dual heteroatom-doped porous carbon from simple precursors. The introduction of N and B heteroatoms leads to the construction of N-B motives and Frustrated Lewis pairs in a microporous architecture which is also rich in point defects. This can improve the strength of adsorption of different reactants (N2 and HMF) and thus their activation. As a result, BNC-2 exhibits a desirable electrochemical NRR and HMF oxidation performance. Gas adsorption experiments have been used as a simple tool to elucidate the relationship between the structure and catalytic activity. This work provides novel and deep insights into the rational design and the origin of activity in metal-free electrocatalysts and enables a physically viable discussion of the active motives, as well as the search for their further applications. Throughout this thesis, the ubiquitous problems of low selectivity and activity of electrochemical NRR are tackled by designing porous carbon-based catalysts with high efficiency and exploring their catalytic mechanisms. The structure-performance relationships and mechanisms of activation of the relatively inert N2 molecules are revealed by either experimental results or DFT calculations. These fundamental understandings pave way for a future optimal design and targeted promotion of NRR catalysts with porous carbon-based structure, as well as study of new N2 activation modes.},
  language  = {en}
}
@phdthesis{PerezMedrano2019,
  author    = {P{\´e}rez Medrano, Cuauht{\´e}moc},
  title     = {Ficci{\´o}n her{\´e}tica},
  publisher = {Universit{\"a}tsverlag Potsdam},
  address   = {Potsdam},
  isbn      = {978-3-86956-454-8},
  issn      = {2629-2548},
  doi       = {10.25932/publishup-42449},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-424490},
  school      = {Universit{\"a}t Potsdam},
  pages     = {226},
  year      = {2019},
  abstract  = {Mit der kubanischen Wirtschaftskrise entstanden neue literarische Gestaltungsprozesse nationaler Identit{\"a}tskonstruktionen. Die vorliegende Analyse geht der zeitgen{\"o}ssischen Literatur Kubas nach, in der soziale, kulturelle und politische Paradoxe der post-revolution{\"a}ren Weltanschauung zum Vorschein kommen und der Figur der „Insel" bzw. „Insularit{\"a}t" eine große Bedeutung f{\"u}r die Neukonfiguration der Nation zukommt. Die „Insularit{\"a}t" dr{\"u}ckt in literarischen Texten verschiedene Aneignungen des Raumes und somit auch eine Weltanschauungen aus. Die literarische Figur der „Insel" kann hypothetisch als „visuelles Ph{\"a}nomen" (Ette 2002) konzipiert werden, das durch soziokulturelle Umst{\"a}nde konfiguriert wird. Unterschiedliche postkommunistische Erfahrungen bilden sog. „erlebnisweltliche" Repr{\"a}sentationen und somit literarische und soziale Identit{\"a}tsbilder. Im Verlauf der Zeit werden die Metapher der „Insel" bzw. der „Insularit{\"a}t" anders beschrieben. Erste Untersuchungen der Metapher der „Insel" bzw. der „Insularit{\"a}t" finden sich in den Texten Noche insular (Lezama Lima 2000) und La isla en peso (Pi{\~n}era 1998). Die Metapher wird in den Begrifflichkeiten der „Simulation" und „Dissimulation" (Sarduy 1982) oder auch einer „visuellen Erscheinung" als „Grund-Ekphrasis" (Pimentel 2001) beschrieben. Demgegen{\"u}ber stellen sp{\"a}tere Arbeiten die literarische Figur der „Insel" als ein Instrument der Dekonstruktion der Nationalliteratur Kubas dar (Rojas 1998; Nuez 1998, Benitez Rojo 1998). In zeitgen{\"o}ssischen Analysen wird die Metapher in ihrer jeweiligen Beziehungen zur Repr{\"a}sentation und zum „Lebenswissen" (Ette 2010) herausgearbeitet. Die Repr{\"a}sentation der "Insel" bzw. der "Insularit{\"a}t" wird in der vorliegenden Arbeit anhand des soziokulturellen Kontextes in den letzten dreißig Jahren u.a. in den Romanen von Abilio Estevez Tuyo es el reino (1998), Atilio Caballero La {\´u}ltima playa (1999), Daniel D{\´i}az Mantilla Regreso a Utop{\´i}a (2007) sowie den Erz{\"a}hlungen von Ena Lucia Portela Huracan (2000), Antonio Jos{\´e} Ponte Un nuevo arte de hacer ruinas (2005), Emerio Medina Isla (2005), Orlando Lu{\´i}s Pardo Tokionama (2009), Ahmel Echeverria Isla (2014) und Anesly Negr{\´i}n Isla a mediod{\´i}a (2014) untersucht.},
  language  = {es}
}
@phdthesis{Pohlenz2019,
  author    = {Pohlenz, Julia},
  title     = {Structural insights into sodium-rich silicate - carbonate glasses and melts},
  doi       = {10.25932/publishup-42382},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-423826},
  school      = {Universit{\"a}t Potsdam},
  pages     = {XXII, 117},
  year      = {2019},
  abstract  = {Carbonate-rich silicate and carbonate melts play a crucial role in deep Earth magmatic processes and their melt structure is a key parameter, as it controls physical and chemical properties. Carbonate-rich melts can be strongly enriched in geochemically important trace elements. The structural incorporation mechanisms of these elements are difficult to study because such melts generally cannot be quenched to glasses, which are usually employed for structural investigations. This thesis investigates the influence of CO2 on the local environments of trace elements contained in silicate glasses with variable CO2 concentrations as well as in silicate and carbonate melts. The compositions studied include sodium-rich peralkaline silicate melts and glasses and carbonate melts similar to those occurring naturally at Oldoinyo Lengai volcano, Tanzania. The local environments of the three elements yttrium (Y), lanthanum (La) and strontium (Sr) were investigated in synthesized glasses and melts using X-ray absorption fine structure (XAFS) spectroscopy. Especially extended X-ray absorption fine structure spectroscopy (EXAFS) provides element specific information on local structure, such as bond lengths, coordination numbers and the degree of disorder. To cope with the enhanced structural disorder present in glasses and melts, EXAFS analysis was based on fitting approaches using an asymmetric distribution function as well as a correlation model according to bond valence theory. Firstly, silicate glasses quenched from high pressure/temperature melts with up to 7.6 wt \% CO2 were investigated. In strongly and extremely peralkaline glasses the local structure of Y is unaffected by the CO2 content (with oxygen bond lengths of ~ 2.29 {\AA}). Contrary, the bond lengths for Sr-O and La-O increase with increasing CO2 content in the strongly peralkaline glasses from ~ 2.53 to ~ 2.57 {\AA} and from ~ 2.52 to ~ 2.54 {\AA}, respectively, while they remain constant in extremely peralkaline glasses (at ~ 2.55 {\AA} and 2.54 {\AA}, respectively). Furthermore, silicate and unquenchable carbonate melts were investigated in-situ at high pressure/temperature conditions (2.2 to 2.6 GPa, 1200 to 1500 °C) using a Paris-Edinburgh press. A novel design of the pressure medium assembly for this press was developed, which features increased mechanical stability as well as enhanced transmittance at relevant energies to allow for low content element EXAFS in transmission. Compared to glasses the bond lengths of Y-O, La-O and Sr-O are elongated by up to + 3 \% in the melt and exhibit higher asymmetric pair distributions. For all investigated silicate melt compositions Y-O bond lengths were found constant at ~ 2.37 {\AA}, while in the carbonate melt the Y-O length increases slightly to 2.41 {\AA}. The La-O bond lengths in turn, increase systematically over the whole silicate - carbonate melt joint from 2.55 to 2.60 {\AA}. Sr-O bond lengths in melts increase from ~ 2.60 to 2.64 {\AA} from pure silicate to silicate-bearing carbonate composition with constant elevated bond length within the carbonate region. For comparison and deeper insight, glass and melt structures of Y and Sr bearing sodium-rich silicate to carbonate compositions were simulated in an explorative ab initio molecular dynamics (MD) study. The simulations confirm observed patterns of CO2-dependent local changes around Y and Sr and additionally provide further insights into detailed incorporation mechanisms of the trace elements and CO2. Principle findings include that in sodium-rich silicate compositions carbon either is mainly incorporated as a free carbonate-group or shares one oxygen with a network former (Si or [4]Al) to form a non-bridging carbonate. Of minor importance are bridging carbonates between two network formers. Here, a clear preference for two [4]Al as adjacent network formers occurs, compared to what a statistical distribution would suggest. In C-bearing silicate melts minor amounts of molecular CO2 are present, which is almost totally dissolved as carbonate in the quenched glasses. The combination of experiment and simulation provides extraordinary insights into glass and melt structures. The new data is interpreted on the basis of bond valence theory and is used to deduce potential mechanisms for structural incorporation of investigated elements, which allow for prediction on their partitioning behavior in natural melts. Furthermore, it provides unique insights into the dissolution mechanisms of CO2 in silicate melts and into the carbonate melt structure. For the latter, a structural model is suggested, which is based on planar CO3-groups linking 7- to 9-fold cation polyhedra, in accordance to structural units as found in the Na-Ca carbonate nyerereite. Ultimately, the outcome of this study contributes to rationalize the unique physical properties and geological phenomena related to carbonated silicate-carbonate melts.},
  language  = {en}
}
@phdthesis{Peter2019,
  author    = {Peter, Franziska},
  title     = {Transition to synchrony in finite Kuramoto ensembles},
  doi       = {10.25932/publishup-42916},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-429168},
  school      = {Universit{\"a}t Potsdam},
  pages     = {vi, 93},
  year      = {2019},
  abstract  = {Synchronisation - die Ann{\"a}herung der Rhythmen gekoppelter selbst oszillierender Systeme - ist ein faszinierendes dynamisches Ph{\"a}nomen, das in vielen biologischen, sozialen und technischen Systemen auftritt. Die vorliegende Arbeit befasst sich mit Synchronisation in endlichen Ensembles schwach gekoppelter selbst-erhaltender Oszillatoren mit unterschiedlichen nat{\"u}rlichen Frequenzen. Das Standardmodell f{\"u}r dieses kollektive Ph{\"a}nomen ist das Kuramoto-Modell - unter anderem aufgrund seiner L{\"o}sbarkeit im thermodynamischen Limes unendlich vieler Oszillatoren. {\"A}hnlich einem thermodynamischen Phasen{\"u}bergang zeigt im Fall unendlich vieler Oszillatoren ein Ordnungsparameter den {\"U}bergang von Inkoh{\"a}renz zu einem partiell synchronen Zustand an, in dem ein Teil der Oszillatoren mit einer gemeinsamen Frequenz rotiert. Im endlichen Fall treten Fluktuationen auf. In dieser Arbeit betrachten wir den bisher wenig beachteten Fall von bis zu wenigen hundert Oszillatoren, unter denen vergleichbar starke Fluktuationen auftreten, bei denen aber ein Vergleich zu Frequenzverteilungen im unendlichen Fall m{\"o}glich ist. Zun{\"a}chst definieren wir einen alternativen Ordnungsparameter zur Feststellung einer kollektiven Mode im endlichen Kuramoto-Modell. Dann pr{\"u}fen wir die Abh{\"a}ngigkeit des Synchronisationsgrades und der mittleren Rotationsfrequenz der kollektiven Mode von Eigenschaften der nat{\"u}rlichen Frequenzverteilung f{\"u}r verschiedene Kopplungsst{\"a}rken. Wir stellen dabei zun{\"a}chst numerisch fest, dass der Synchronisationsgrad stark von der Form der Verteilung (gemessen durch die Kurtosis) und die Rotationsfrequenz der kollektiven Mode stark von der Asymmetrie der Verteilung (gemessen durch die Schiefe) der nat{\"u}rlichen Frequenzen abh{\"a}ngt. Beides k{\"o}nnen wir im thermodynamischen Limes analytisch verifizieren. Mit diesen Ergebnissen k{\"o}nnen wir Erkenntnisse anderer Autoren besser verstehen und verallgemeinern. Etwas abseits des roten Fadens dieser Arbeit finden wir außerdem einen analytischen Ausdruck f{\"u}r die Volumenkontraktion im Phasenraum. Der zweite Teil der Arbeit konzentriert sich auf den ordnenden Effekt von Fluktuationen, die durch die Endlichkeit des Systems zustande kommen. Im unendlichen Modell sind die Oszillatoren eindeutig in koh{\"a}rent und inkoh{\"a}rent und damit in geordnet und ungeordnet getrennt. Im endlichen Fall k{\"o}nnen die auftretenden Fluktuationen zus{\"a}tzliche Ordnung unter den asynchronen Oszillatoren erzeugen. Das grundlegende Prinzip, die rauschinduzierte Synchronisation, ist aus einer Reihe von Publikationen bekannt. Unter den gekoppelten Oszillatoren n{\"a}hern sich die Phasen aufgrund der Fluktuationen des Ordnungsparameters an, wie wir einerseits direkt numerisch zeigen und andererseits mit einem Synchronisationsmaß aus der gerichteten Statistik zwischen Paaren passiver Oszillatoren nachweisen. Wir bestimmen die Abh{\"a}ngigkeit dieses Synchronisationsmaßes vom Verh{\"a}ltnis von paarweiser nat{\"u}rlicher Frequenzdifferenz zur Varianz der Fluktuationen. Dabei finden wir eine gute {\"U}bereinstimmung mit einem einfachen analytischen Modell, in welchem wir die deterministischen Fluktuationen des Ordnungsparameters durch weißes Rauschen ersetzen.},
  language  = {en}
}
@phdthesis{Perlich2019,
  author    = {Perlich, Anja},
  title     = {Digital collaborative documentation in mental healthcare},
  doi       = {10.25932/publishup-44029},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-440292},
  school      = {Universit{\"a}t Potsdam},
  pages     = {x, 135},
  year      = {2019},
  abstract  = {With the growth of information technology, patient attitudes are shifting - away from passively receiving care towards actively taking responsibility for their well- being. Handling doctor-patient relationships collaboratively and providing patients access to their health information are crucial steps in empowering patients. In mental healthcare, the implicit consensus amongst practitioners has been that sharing medical records with patients may have an unpredictable, harmful impact on clinical practice. In order to involve patients more actively in mental healthcare processes, Tele-Board MED (TBM) allows for digital collaborative documentation in therapist-patient sessions. The TBM software system offers a whiteboard-inspired graphical user interface that allows therapist and patient to jointly take notes during the treatment session. Furthermore, it provides features to automatically reuse the digital treatment session notes for the creation of treatment session summaries and clinical case reports. This thesis presents the development of the TBM system and evaluates its effects on 1) the fulfillment of the therapist's duties of clinical case documentation, 2) patient engagement in care processes, and 3) the therapist-patient relationship. Following the design research methodology, TBM was developed and tested in multiple evaluation studies in the domains of cognitive behavioral psychotherapy and addiction care. The results show that therapists are likely to use TBM with patients if they have a technology-friendly attitude and when its use suits the treatment context. Support in carrying out documentation duties as well as fulfilling legal requirements contributes to therapist acceptance. Furthermore, therapists value TBM as a tool to provide a discussion framework and quick access to worksheets during treatment sessions. Therapists express skepticism, however, regarding technology use in patient sessions and towards complete record transparency in general. Patients expect TBM to improve the communication with their therapist and to offer a better recall of discussed topics when taking a copy of their notes home after the session. Patients are doubtful regarding a possible distraction of the therapist and usage in situations when relationship-building is crucial. When applied in a clinical environment, collaborative note-taking with TBM encourages patient engagement and a team feeling between therapist and patient. Furthermore, it increases the patient's acceptance of their diagnosis, which in turn is an important predictor for therapy success. In summary, TBM has a high potential to deliver more than documentation support and record transparency for patients, but also to contribute to a collaborative doctor-patient relationship. This thesis provides design implications for the development of digital collaborative documentation systems in (mental) healthcare as well as recommendations for a successful implementation in clinical practice.},
  language  = {en}
}
@phdthesis{Otte2019,
  author    = {Otte, Fabian},
  title     = {C-Arylglykoside und Chalkone},
  doi       = {10.25932/publishup-43430},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-434305},
  school      = {Universit{\"a}t Potsdam},
  pages     = {XI, 201},
  year      = {2019},
  abstract  = {Im bis heute andauernden Zeitalter der wissenschaftlichen Medizin, konnte ein breites Spektrum von Wirkstoffen zur Behandlung diverser Krankheiten zusammengetragen werden. Dennoch hat es sich die organische Synthesechemie zur Aufgabe gemacht, dieses Spektrum auf neuen oder bekannten Wegen und aus verschiedenen Gr{\"u}nden zu erweitern. Zum einen ist das Vorkommen bestimmter Verbindungen in der Natur h{\"a}ufig limitiert, sodass synthetische Methoden immer {\"o}fter an Stelle eines weniger nachhaltigen Abbaus treten. Zum anderen kann durch Derivatisierung und Wirkstoffanpassung die physiologische Wirkung oder die Bioverf{\"u}gbarkeit eines Wirkstoffes erh{\"o}ht werden. In dieser Arbeit konnten einige Vertreter der bekannten Wirkstoffklassen C-Arylglykoside und Chalkone durch den Schl{\"u}sselschritt der Palladium-katalysierten MATSUDA-HECK-Reaktion synthetisiert werden. Dazu wurden im Fall der C-Arylglykoside zun{\"a}chst unges{\"a}ttigte Kohlenhydrate (Glykale) {\"u}ber eine Ruthenium-katalysierte Zyklisierungsreaktion dargestellt. Diese wurden im Anschluss mit unterschiedlich substituierten Diazoniumsalzen in der oben erw{\"a}hnten Palladium-katalysierten Kupplungsreaktion zur Reaktion gebracht. Bei der Auswertung der analytischen Daten konnte festgestellt werden, dass stets die trans-Diastereomere gebildet wurden. Im Anschluss konnte gezeigt werden, dass die Doppelbindungen dieser Verbindungen durch Hydrierung, Dihydroxylierung oder Epoxidierung funktionalisiert werden k{\"o}nnen. Auf diesem Wege konnte u. a. eine dem Diabetesmedikament Dapagliflozin {\"a}hnliche Verbindung hergestellt werden. Im zweiten Teil der Arbeit wurden Arylallylchromanone durch die MATSUDA-HECK-Reaktion von verschiedenen 8-Allylchromanonen mit Diazoniumsalzen dargestellt. Dabei konnte beobachtet werden, dass eine MOM-Schutzgruppe in 7-Position der Molek{\"u}le die Darstellung von Produktgemischen unterdr{\"u}ckt und jeweils nur eine der m{\"o}glichen Verbindungen gebildet wird. Die Lage der Doppelbindung konnte mittels 2D-NMR-Untersuchungen lokalisiert werden. In Kooperation mit der theoretischen Chemie sollte durch Berechnungen untersucht werden, wie die beobachteten Verbindungen entstehen. Durch eine auftretende Wechselwirkung innerhalb des Molek{\"u}ls konnte allerdings keine explizite Aussage getroffen werden. Im Anschluss sollten die erhaltenen Verbindungen in einer allylischen Oxidation zu Chalkonen umgesetzt werden. Die Ruthenium-katalysierten Methoden zeigten u. a. keine Eignung. Es konnte allerdings eine metallfreie, Mikrowellen-unterst{\"u}tzte Methode erfolgreich erprobt werden, sodass die Darstellung einiger Vertreter dieser physiologisch aktiven Stoffklasse gelang.},
  language  = {de}
}
@phdthesis{Numberger2019,
  author    = {Numberger, Daniela},
  title     = {Urban wastewater and lakes as habitats for bacteria and potential vectors for pathogens},
  doi       = {10.25932/publishup-43709},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-437095},
  school      = {Universit{\"a}t Potsdam},
  pages     = {VI, 130},
  year      = {2019},
  abstract  = {Wasser ist lebensnotwendig und somit eine essentielle Ressource. Jedoch sind unsere S{\"u}ßwasser-Ressourcen begrenzt und ihre Erhaltung daher besonders wichtig. Verschmutzungen mit Chemikalien und Krankheitserregern, die mit einer wachsenden Bev{\"o}lkerung und Urbanisierung einhergehen, verschlechtern die Qualit{\"a}t unseres S{\"u}ßwassers. Außerdem kann Wasser als {\"U}bertragungsvektor f{\"u}r Krankheitserreger dienen und daher wasserb{\"u}rtige Krankheiten verursachen. Der Leibniz-Forschungsverbund INFECTIONS'21 untersuchte innerhalb der interdisziplin{\"a}ren Forschungsgruppe III - „Wasser", Gew{\"a}sser als zentralen Mittelpunkt f{\"u}r Krankheiterreger. Dabei konzentrierte man sich auf Clostridioides difficile sowie avi{\"a}re Influenza A-Viren, von denen angenommen wird, dass sie in die Gew{\"a}sser ausgeschieden werden. Ein weiteres Ziel bestand darin, die bakterielle Gemeinschaften eines Kl{\"a}rwerkes der deutschen Hauptstadt Berlin zu charakterisieren, um anschließend eine Bewertung des potentiellen Gesundheitsrisikos geben zu k{\"o}nnen. Bakterielle Gemeinschaften des Roh- und Klarwassers aus dem Kl{\"a}rwerk unterschieden sich signifikant voneinander. Der Anteil an Darm-/F{\"a}kalbakterien war relativ niedrig und potentielle Darmpathogene wurden gr{\"o}ßtenteils aus dem Rohwasser entfernt. Ein potentielles Gesundheitsrisiko konnte allerdings von potentiell pathogenen Legionellen wie L. lytica festgestellt werden, deren relative Abundanz im Klarwasser h{\"o}her war als im Rohwasser. Es wurden außerdem drei C. difficile-Isolate aus den Kl{\"a}rwerk-Rohwasser und einem st{\"a}dtischen Badesee in Berlin (Weisser See) gewonnen und sequenziert. Die beiden Isolate aus dem Kl{\"a}rwerk tragen keine Toxin-Gene, wohingegen das Isolat aus dem See Toxin-Gene besitzt. Alle drei Isolate sind sehr nah mit humanen St{\"a}mmen verwandt. Dies deutet auf ein potentielles, wenn auch sporadisches Gesundheitsrisiko hin. (Avi{\"a}re) Influenza A-Viren wurden in 38.8\% der untersuchten Sedimentproben mittels PCR detektiert, aber die Virusisolierung schlug fehl. Ein Experiment mit beimpften Wasser- und Sedimentproben zeigte, dass f{\"u}r die Isolierung aus Sedimentproben eine relativ hohe Viruskonzentration n{\"o}tig ist. In Wasserproben ist jedoch ein niedriger Titer an Influenza A-Viren ausreichend, um eine Infektion auszul{\"o}sen. Es konnte zudem auch festgestellt werden, dass sich „Madin-Darby Canine Kidney (MDCK)―-Zellkulturen im Gegensatz zu embryonierten H{\"u}hnereiern besser eignen, um Influenza A-Viren aus Sediment zu isolieren. Zusammenfassend l{\"a}sst sich sagen, dass diese Arbeit m{\"o}gliche Gesundheitsrisiken aufgedeckt hat, wie etwa durch Legionellen im untersuchten Berliner Kl{\"a}rwerk, deren relative Abundanz in gekl{\"a}rtem Abwasser h{\"o}her ist als im Rohwasser. Desweiteren wird indiziert, dass Abwasser und Gew{\"a}sser als Reservoir und Vektor f{\"u}r pathogene Organismen dienen k{\"o}nnen, selbst f{\"u}r nicht-typische Wasser-Pathogene wie C. difficile.},
  language  = {en}
}
@phdthesis{Noack2019,
  author    = {Noack, Sebastian},
  title     = {Poly(lactide)-based amphiphilic block copolymers},
  doi       = {10.25932/publishup-43616},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-436168},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xvii, 148},
  year      = {2019},
  abstract  = {Due to its bioavailability and (bio)degradability, poly(lactide) (PLA) is an interesting polymer that is already being used as packaging material, surgical seam, and drug delivery system. Dependent on various parameters such as polymer composition, amphiphilicity, sample preparation, and the enantiomeric purity of lactide, PLA in an amphiphilic block copolymer can affect the self-assembly behavior dramatically. However, sizes and shapes of aggregates have a critical effect on the interactions between biological and drug delivery systems, where the general understanding of these polymers and their ability to influence self-assembly is of significant interest in science. The first part of this thesis describes the synthesis and study of a series of linear poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA)-based amphiphilic block copolymers with varying PLA (hydrophobic), and poly(ethylene glycol) (PEG) (hydrophilic) chain lengths and different block copolymer sequences (PEG-PLA and PLA-PEG). The PEG-PLA block copolymers were synthesized by ring-opening polymerization of lactide initiated by a PEG-OH macroinitiator. In contrast, the PLA-PEG block copolymers were produced by a Steglich-esterification of modified PLA with PEG-OH. The aqueous self-assembly at room temperature of the enantiomerically pure PLLA-based block copolymers and their stereocomplexed mixtures was investigated by dynamic light scattering (DLS), transmission electron microscopy (TEM), wide-angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC). Spherical micelles and worm-like structures were produced, whereby the obtained self-assembled morphologies were affected by the lactide weight fraction in the block copolymer and self-assembly time. The formation of worm-like structures increases with decreasing PLA-chain length and arises from spherical micelles, which become colloidally unstable and undergo an epitaxial fusion with other micelles. As shown by DSC experiments, the crystallinity of the corresponding PLA blocks increases within the self-assembly time. However, the stereocomplexed self-assembled structures behave differently from the parent polymers and result in irregular-shaped clusters of spherical micelles. Additionally, time-dependent self-assembly experiments showed a transformation, from already self-assembled morphologies of different shapes to more compact micelles upon stereocomplexation. In the second part of this thesis, with the objective to influence the self-assembly of PLA-based block copolymers and its stereocomplexes, poly(methyl phosphonate) (PMeP) and poly(isopropyl phosphonate) (PiPrP) were produced by ring-opening polymerization to implement an alternative to the hydrophilic block PEG. Although, the 1,8 diazabicyclo[5.4.0]unde 7 ene (DBU) or 1,5,7 triazabicyclo[4.4.0]dec-5-ene (TBD) mediated synthesis of the corresponding poly(alkyl phosphonate)s was successful, however, not so the polymerization of copolymers with PLA-based precursors (PLA-homo polymers, and PEG-PLA block copolymers). Transesterification, obtained by 1H-NMR spectroscopy, between the poly(phosphonate)- and PLA block caused a high-field shifted peak split of the methine proton in the PLA polymer chain, with split intensities depending on the used catalyst (DBU for PMeP, and TBD for PiPrP polymerization). An additional prepared block copolymer PiPrP-PLLA that wasn't affected in its polymer sequence was finally used for self-assembly experiments with PLA-PEG and PEG-PLA mixing. This work provides a comprehensive study of the self-assembly behavior of PLA-based block copolymers influenced by various parameters such as polymer block lengths, self-assembly time, and stereocomplexation of block copolymer mixtures.},
  language  = {en}
}
@phdthesis{Nikkhoo2019,
  author    = {Nikkhoo, Mehdi},
  title     = {Analytical and numerical elastic dislocation models of volcano deformation processes},
  doi       = {10.25932/publishup-42972},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-429720},
  school      = {Universit{\"a}t Potsdam},
  pages     = {x, 175},
  year      = {2019},
  abstract  = {The advances in modern geodetic techniques such as the global navigation satellite system (GNSS) and synthetic aperture radar (SAR) provide surface deformation measurements with an unprecedented accuracy and temporal and spatial resolutions even at most remote volcanoes on Earth. Modelling of the high-quality geodetic data is crucial for understanding the underlying physics of volcano deformation processes. Among various approaches, mathematical models are the most effective for establishing a quantitative link between the surface displacements and the shape and strength of deformation sources. Advancing the geodetic data analyses and hence, the knowledge on the Earth's interior processes, demands sophisticated and efficient deformation modelling approaches. Yet the majority of these models rely on simplistic assumptions for deformation source geometries and ignore complexities such as the Earth's surface topography and interactions between multiple sources. This thesis addresses this problem in the context of analytical and numerical volcano deformation modelling. In the first part, new analytical solutions for triangular dislocations (TDs) in uniform infinite and semi-infinite elastic media have been developed. Through a comprehensive investigation, the locations and causes of artefact singularities and numerical instabilities associated with TDs have been determined and these long-standing drawbacks have been addressed thoroughly. This approach has then been extended to rectangular dislocations (RDs) with full rotational degrees of freedom. Using this solution in a configuration of three orthogonal RDs a compound dislocation model (CDM) has been developed. The CDM can represent generalized volumetric and planar deformation sources efficiently. Thus, the CDM is relevant for rapid inversions in early warning systems and can also be used for detailed deformation analyses. In order to account for complex source geometries and realistic topography in the deformation models, in this thesis the boundary element method (BEM) has been applied to the new solutions for TDs. In this scheme, complex surfaces are simulated as a continuous mesh of TDs that may possess any displacement or stress boundary conditions in the BEM calculations. In the second part of this thesis, the developed modelling techniques have been applied to five different real-world deformation scenarios. As the first and second case studies the deformation sources associated with the 2015 Calbuco eruption and 2013-2016 Copahue inflation period have been constrained by using the CDM. The highly anisotropic source geometries in these two cases highlight the importance of using generalized deformation models such as the CDM, for geodetic data inversions. The other three case studies in this thesis involve high-resolution dislocation models and BEM calculations. As the third case, the 2013 pre-explosive inflation of Volc{\´a}n de Colima has been simulated by using two ellipsoidal cavities, which locate zones of pressurization in the volcano's lava dome. The fourth case study, which serves as an example for volcanotectonics interactions, the 3-D kinematics of an active ring-fault at Tend{\"u}rek volcano has been investigated through modelling displacement time series over the 2003-2010 time period. As the fifth example, the deformation sources associated with North Korea's underground nuclear test in September 2017 have been constrained. These examples demonstrate the advancement and increasing level of complexity and the general applicability of the developed dislocation modelling techniques. This thesis establishes a unified framework for rapid and high-resolution dislocation modelling, which in addition to volcano deformations can also be applied to tectonic and humanmade deformations.},
  language  = {en}
}
@phdthesis{Nikaj2019,
  author    = {Nikaj, Adriatik},
  title     = {Restful choreographies},
  doi       = {10.25932/publishup-43890},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-438903},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xix, 146},
  year      = {2019},
  abstract  = {Business process management has become a key instrument to organize work as many companies represent their operations in business process models. Recently, business process choreography diagrams have been introduced as part of the Business Process Model and Notation standard to represent interactions between business processes, run by different partners. When it comes to the interactions between services on the Web, Representational State Transfer (REST) is one of the primary architectural styles employed by web services today. Ideally, the RESTful interactions between participants should implement the interactions defined at the business choreography level. The problem, however, is the conceptual gap between the business process choreography diagrams and RESTful interactions. Choreography diagrams, on the one hand, are modeled from business domain experts with the purpose of capturing, communicating and, ideally, driving the business interactions. RESTful interactions, on the other hand, depend on RESTful interfaces that are designed by web engineers with the purpose of facilitating the interaction between participants on the internet. In most cases however, business domain experts are unaware of the technology behind web service interfaces and web engineers tend to overlook the overall business goals of web services. While there is considerable work on using process models during process implementation, there is little work on using choreography models to implement interactions between business processes. This thesis addresses this research gap by raising the following research question: How to close the conceptual gap between business process choreographies and RESTful interactions? This thesis offers several research contributions that jointly answer the research question. The main research contribution is the design of a language that captures RESTful interactions between participants---RESTful choreography modeling language. Formal completeness properties (with respect to REST) are introduced to validate its instances, called RESTful choreographies. A systematic semi-automatic method for deriving RESTful choreographies from business process choreographies is proposed. The method employs natural language processing techniques to translate business interactions into RESTful interactions. The effectiveness of the approach is shown by developing a prototypical tool that evaluates the derivation method over a large number of choreography models. In addition, the thesis proposes solutions towards implementing RESTful choreographies. In particular, two RESTful service specifications are introduced for aiding, respectively, the execution of choreographies' exclusive gateways and the guidance of RESTful interactions.},
  language  = {en}
}
@phdthesis{Nguyen2019,
  author    = {Nguyen, Quyet Doan},
  title     = {Electro-acoustical probing of space-charge and dipole-polarization profiles in polymer dielectrics for electret and electrical-insulation applications},
  doi       = {10.25932/publishup-44562},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-445629},
  school      = {Universit{\"a}t Potsdam},
  pages     = {105},
  year      = {2019},
  abstract  = {Electrets are dielectrics with quasi-permanent electric charge and/or dipoles, sometimes can be regarded as an electric analogy to a magnet. Since the discovery of the excellent charge retention capacity of poly(tetrafluoro ethylene) and the invention of the electret microphone, electrets have grown out of a scientific curiosity to an important application both in science and technology. The history of electret research goes hand in hand with the quest for new materials with better capacity at charge and/or dipole retention. To be useful, electrets normally have to be charged/poled to render them electro-active. This process involves electric-charge deposition and/or electric dipole orientation within the dielectrics ` surfaces and bulk. Knowledge of the spatial distribution of electric charge and/or dipole polarization after their deposition and subsequent decay is crucial in the task to improve their stability in the dielectrics. Likewise, for dielectrics used in electrical insulation applications, there are also needs for accumulated space-charge and polarization spatial profiling. Traditionally, space-charge accumulation and large dipole polarization within insulating dielectrics is considered undesirable and harmful to the insulating dielectrics as they might cause dielectric loss and could lead to internal electric field distortion and local field enhancement. High local electric field could trigger several aging processes and reduce the insulating dielectrics' lifetime. However, with the advent of high-voltage DC transmission and high-voltage capacitor for energy storage, these are no longer the case. There are some overlapped between the two fields of electrets and electric insulation. While quasi-permanently trapped electric-charge and/or large remanent dipole polarization are the requisites for electret operation, stably trapped electric charge in electric insulation helps reduce electric charge transport and overall reduced electric conductivity. Controlled charge trapping can help in preventing further charge injection and accumulation as well as serving as field grading purpose in insulating dielectrics whereas large dipole polarization can be utilized in energy storage applications. In this thesis, the Piezoelectrically-generated Pressure Steps (PPSs) were employed as a nondestructive method to probe the electric-charge and dipole polarization distribution in a range of thin film (several hundred micron) polymer-based materials, namely polypropylene (PP), low-density polyethylene/magnesium oxide (LDPE/MgO) nanocomposites and poly(vinylidene fluoride-co- trifluoro ethylene) (P(VDF-TrFE)) copolymer. PP film surface-treated with phosphoric acid to introduce surfacial isolated nanostructures serves as example of 2-dimensional nano-composites whereas LDPE/MgO serves as the case of 3-dimensional nano-composites with MgO nano-particles dispersed in LDPE polymer matrix. It is evidenced that the nanoparticles on the surface of acid-treated PP and in the bulk of LDPE/MgO nanocomposites improve charge trapping capacity of the respective material and prevent further charge injection and transport and that the enhanced charge trapping capacity makes PP and LDPE/MgO nanocomposites potential materials for both electret and electrical insulation applications. As for PVDF and VDF-based copolymers, the remanent spatial polarization distribution depends critically on poling method as well as specific parameters used in the respective poling method. In this work, homogeneous polarization poling of P(VDF-TrFE) copolymers with different VDF-contents have been attempted with hysteresis cyclical poling. The behaviour of remanent polarization growth and spatial polarization distribution are reported and discussed. The Piezoelectrically-generated Pressure Steps (PPSs) method has proven as a powerful method for the charge storage and transport characterization of a wide range of polymer material from nonpolar, to polar, to polymer nanocomposites category.},
  language  = {en}
}
@phdthesis{Nasery2019,
  author    = {Nasery, Mustafa},
  title     = {The success and failure of civil service reforms in Afghanistan},
  doi       = {10.25932/publishup-44473},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-444738},
  school      = {Universit{\"a}t Potsdam},
  pages     = {viii, 258},
  year      = {2019},
  abstract  = {The Government will create a motivated, merit-based, performance-driven, and professional civil service that is resistant to temptations of corruption and which provides efficient, effective and transparent public services that do not force customers to pay bribes. — (GoIRA, 2006, p. 106) We were in a black hole! We had an empty glass and had nothing from our side to fill it with! Thus, we accepted anything anybody offered; that is how our glass was filled; that is how we reformed our civil service. — (Former Advisor to IARCSC, personal communication, August 2015) How and under what conditions were the post-Taleban Civil Service Reforms of Afghanistan initiated? What were the main components of the reforms? What were their objectives and to which extent were they achieved? Who were the leading domestic and foreign actors involved in the process? Finally, what specific factors influenced the success and failure Afghanistan's Civil Service Reforms since 2002? Guided by such fundamental questions, this research studies the wicked process of reforming the Afghan civil service in an environment where a variety of contextual, programmatic, and external factors affected the design and implementation of reforms that were entirely funded and technically assisted by the international community. Focusing on the core components of reforms—recruitment, remuneration, and appraisal of civil servants—the qualitative study provides a detailed picture of the pre-reform civil service and its major human resources developments in the past. Following discussions on the content and purposes of the main reform programs, it will then analyze the extent of changes in policies and practices by examining the outputs and effects of these reforms. Moreover, the study defines the specific factors that led the reforms toward a situation where most of the intended objectives remain unachieved. Doing so, it explores and explains how an overwhelming influence of international actors with conflicting interests, large-scale corruption, political interference, networks of patronage, institutionalized nepotism, culturally accepted cronyism and widespread ethnic favoritism created a very complex environment and prevented the reforms from transforming Afghanistan's patrimonial civil service into a professional civil service, which is driven by performance and merit.},
  language  = {en}
}
@phdthesis{Nagel2019,
  author    = {Nagel, Oliver},
  title     = {Amoeboid cells as a transport system for micro-objects},
  doi       = {10.25932/publishup-44219},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-442192},
  school      = {Universit{\"a}t Potsdam},
  pages     = {x, 84},
  year      = {2019},
  abstract  = {Due to advances in science and technology towards smaller and more powerful processing units, the fabrication of micrometer sized machines for different tasks becomes more and more possible. Such micro-robots could revolutionize medical treatment of diseases and shall support to work on other small machines. Nevertheless, scaling down robots and other devices is a challenging task and will probably remain limited in near future. Over the past decade the concept of bio-hybrid systems has proved to be a promising approach in order to advance the further development of micro-robots. Bio-hybrid systems combine biological cells with artificial components, thereby benefiting from the functionality of living biological cells. Cell-driven micro-transport is one of the most prominent applications in the emerging field of these systems. So far, micrometer sized cargo has been successfully transported by means of swimming bacterial cells. The potential of motile adherent cells as transport systems has largely remained unexplored. This thesis concentrates on the social amoeba Dictyostelium discoideum as a potential candidate for an amoeboid bio-hybrid transport system. The use of this model organism comes with several advantages. Due to the unspecific properties of Dictyostelium adhesion, a wide range of different cargo materials can be used for transport. As amoeboid cells exceed bacterial cells in size by one order of magnitude, also the size of an object carried by a single cell can also be much larger for an amoeba. Finally it is possible to guide the cell-driven transport based on the chemotactic behavior of the amoeba. Since cells undergo a developmentally induced chemotactic aggregation, cargo could be assembled in a self-organized manner into a cluster. It is also possible to impose an external chemical gradient to guide the amoeboid transport system to a desired location. To establish Dictyostelium discoideum as a possible candidate for bio-hybrid transport systems, this thesis will first investigate the movement of single cells. Secondly, the interaction of cargo and cells will be studied. Eventually, a conceptional proof will be conducted, that the cheomtactic behavior can be exploited either to transport a cargo self-organized or through an external chemical source.},
  language  = {en}
}
@phdthesis{Michalczyk2019,
  author    = {Michalczyk, Anna},
  title     = {Modelling of nitrogen cycles in intensive winter wheat-summer maize double cropping systems in the North China Plain},
  doi       = {10.25932/publishup-44421},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-444213},
  school      = {Universit{\"a}t Potsdam},
  pages     = {X, 154},
  year      = {2019},
  abstract  = {The North China Plain (NCP) is one of the most productive and intensive agricultural regions in China. High doses of mineral nitrogen (N) fertiliser, often combined with flood irrigation, are applied, resulting in N surplus, groundwater depletion and environmental pollution. The objectives of this thesis were to use the HERMES model to simulate the N cycle in winter wheat (Triticum aestivum L.)-summer maize (Zea mays L.) double crop rotations and show the performance of the HERMES model, of the new ammonia volatilisation sub-module and of the new nitrification inhibition tool in the NCP. Further objectives were to assess the models potential to save N and water on plot and county scale, as well as on short and long-term. Additionally, improved management strategies with the help of a model-based nitrogen fertiliser recommendation (NFR) and adapted irrigation, should be found. Results showed that the HERMES model performed well under growing conditions of the NCP and was able to describe the relevant processes related to soil-plant interactions concerning N and water during a 2.5 year field experiment. No differences in grain yield between the real-time model-based NFR and the other treatments of the experiments on plot scale in Quzhou County could be found. Simulations with increasing amounts of irrigation resulted in significantly higher N leaching, higher N requirements of the NFR and reduced yields. Thus, conventional flood irrigation as currently practised by the farmers bears great uncertainties and exact irrigation amounts should be known for future simulation studies. In the best-practice scenario simulation on plot-scale, N input and N leaching, but also irrigation water could be reduced strongly within 2 years. Thus, the model-based NFR in combination with adapted irrigation had the highest potential to reduce nitrate leaching, compared to farmers practice and mineral N (Nmin)-reduced treatments. Also the calibrated and validated ammonia volatilisation sub-module of the HERMES model worked well under the climatic and soil conditions of northern China. Simple ammonia volatilisation approaches gave also satisfying results compared to process-oriented approaches. During the simulation with Ammonium sulphate Nitrate with nitrification inhibitor (ASNDMPP) ammonia volatilisation was higher than in the simulation without nitrification inhibitor, while the result for nitrate leaching was the opposite. Although nitrification worked well in the model, nitrification-born nitrous oxide emissions should be considered in future. Results of the simulated annual long-term (31 years) N losses in whole Quzhou County in Hebei Province were 296.8 kg N ha-1 under common farmers practice treatment and 101.7 kg N ha-1 under optimised treatment including NFR and automated irrigation (OPTai). Spatial differences in simulated N losses throughout Quzhou County, could only be found due to different N inputs. Simulations of an optimised treatment, could save on average more than 260 kg N ha-1a-1 from fertiliser input and 190 kg N ha-1a-1 from N losses and around 115.7 mm a-1 of water, compared to farmers practice. These long-term simulation results showed lower N and water saving potential, compared to short-term simulations and underline the necessity of long-term simulations to overcome the effect of high initial N stocks in soil. Additionally, the OPTai worked best on clay loam soil except for a high simulated denitrification loss, while the simulations using farmers practice irrigation could not match the actual water needs resulting in yield decline, especially for winter wheat. Thus, a precise adaption of management to actual weather conditions and plant growth needs is necessary for future simulations. However, the optimised treatments did not seem to be able to maintain the soil organic matter pools, even with full crop residue input. Extra organic inputs seem to be required to maintain soil quality in the optimised treatments. HERMES is a relatively simple model, with regard to data input requirements, to simulate the N cycle. It can offer interpretation of management options on plot, on county and regional scale for extension and research staff. Also in combination with other N and water saving methods the model promises to be a useful tool.},
  language  = {en}
}